Process for the removal of skins of filbert nuts



Patented Feb. 17, 1942 PROCESS FOR THE REMOVAL OF SKINS OF FILBERT NUTSEdward B. Edes, Lebanon, Oreg.

N Drawing. Application March 22, 1940, Serial No. 325,368

4 Claims.

My process relates to other edible nuts as well as filberts. Heretofore,according to my knowledge of the art, the removal of the skins from thenut meats of filberts was accomplished by immersion of the nut kernelsin an alkaline solution, preferably brought to and held at boilingpoint, so as to expedite the process; and the time fixed for suchimmersion was from 1 to 7 minutes, with a longer period being requiredif unheated alkaline solution is used. The purpose of such procedureprobably was to efiect complete saponification of the oleaginouscomponent of the nut skins; such component apparently being consideredas constituting the medium providing the adherence of the skin to thenut meat.

I have discovered, however, that if'removal of the skin is attempted byan alkaline solution discoloration of the nut meat from its normal ivorycolor to a color resembling more or less dark mahogany will result andbesides the removal of the skin is not facilitated. This discolorationis plainly seen in the marginal portion of the nut meat, if the kernelbe cut crosswise to its growth axis. The discoloration may penetrate themarginal portion of the nut meat to a depth of sth of an inch. I furtherdiscovered that this discoloration of the nut is speeded and intensifiedby the immersion of the nut kernels in a hot or boiling alkalinesolution.

The object of my invention is to accomplish the removal of the skinsfrom the kernels without injury or discoloration of the nut meat.

My experiments show that the use of an alkaline solution appearsnecessary as a preliminary step for efiecting the loosening of the skinsfrom the nut meats, and saponification of the oleaginous component ofthe skin is thus produced; but it is my belief that the skin containsonly a small amount of oil.

I have discovered that a safe, and likewise effective way of removingthe skins is to subject the nut kernels to successive immersions, first,for a limited time, in a weak, cold, alkaline solution, and then for alimited time, in a weak acid solution.

By my process the kernels are first immersed in a solution at normaltemperature of approximately 3% caustic soda (sodium hydroxide), orequivalent reagent, for a period of from 1 to 4 minutes, depending uponthe thickness of the skins, and the variety of the filberts to betreated, which must be taken into account by the operator. He mustdetermine the required time of immersion, by previous tests made with asample of nuts taken from the volume of nuts to be treated. This samplemust be immersed in the alkaline solution for the minimum period, andthen a kernel taken out and cut across its axis of growth and the cutsurface of the nut observed. 1f immersed for too long a period of timein the alkaline solution, discoloration of the marginal portion of thenut meat will appear as above mentioned, and the time must be shortened.This step may also be controlled by watching the alkaline solution. Whenthis begins to acquire a color resembling dark mahogany, such indicatesthat alkaline solution immersion has progressed to the extentpermissible, and the kernels should be immediately removed from thesolution. On the other hand, the immersion must also be for a suiflcientperiod to render the second step of my process effective for looseningthe skins.

I have successfully used solutions made up with borax, carbonate ofsoda, or bicarbonate of soda. In short, any chemical may be employed tomake the solution which I will designate this solution as an alkalinesolution.

The temperature of the solution may be that of the atmosphere prevailingat the time my process is used.

The time limit of immersion of the nut kernels in the alkaline solutionis critical, and therefore the time must be limited to a shorter periodthan would efiect deleteriously the nut meat.

The immersion of the nut kernels in the alkaline solution does notloosen the skin from the nut meat so that the skin may be removed by adislodging force, as for example by the impingement upon the kernels ofa stream of water under pressure, or equivalent procedure.

The immersion of the kernels in the alkaline solution merely puts thekernels in condition for having their skins loosened by the next step ofmy process. This step consists in immersing the kernels in aweak--approximately 2 to 4% acid solution hydrochloric, acetic, andcitric acids have been successfully used by me for a period of from 1 to4 minutes; the required length of immersion in the acid solution is tobe determined as hereinafter stated.

Before placing the kernels in the acid solution, after their immersionin the alkaline solution, they should, preferably be thoroughly washed,so as to rinse ofi the alkaline solution adhering to the kernels,thereby reducing the cost of acid solution required by my process byavoiding waste of acid solution in the neutralizing of the alkalinesolution adhering to the kernels.

After the skins have been loosened from the nut meats they may beremoved by placing the processed kernels in a body of water subjected tovigorous agitation; or by the impingement up- 7 on the kernels ofstreams of water under pressure.

The loosening of the skins by the acid immersion so that they willreadily separate from the nut meats, may be determined by placing a fewof the kernels in a jar filled with water and vigorously shaking thejar. If the two steps of my process have been properly performed, theskins of the kernels will soon become detached from the nut meats andwill be seen floating in the water.

If the skins do not become detached from the nut meats by this test,then either the immersion of the kernels in the alkaline or saponifyingsolution, or their immersion in the acid solution,,or both immersionshave not been properly timed. In this connection attention must again becalled to the fact that the proper limitation of the immersion of thenut kernels in the alkaline solution is a critical procedure. Butslightly excessive immersion of the kernels in the acid solution isnegligible.

Because of the variance in the thickness of skins in dryness and otherfactors in different varieties and crops of nuts, it is impossible tospecify fixed periods for the immersions of the kernels in eithersolution; but the operator must himself more or less fix the periods ofsaid immersions by applying his knowledge gained by experience inpractising my process. In other words, the operator will by experiencelearn to fix such periods approximately by the appearance of the nuts ortheir kernels; and then by taking a sample of the volume of nut kernelsto be processed and giving this sample a laboratory treatment inaccordance with the requirements of my process as above described, thetime periods for each immersion may be readily and safely fixed for thetreatment of the whole volume of nut kernels. After the nut meats aretaken from the acid solution, they must be thoroughly Washed to removeall adhering acid solution. But this is accomplished in the removal ofthe skins from the nut meats by the application of a skin dislodgingforce through water as the medium as above mentioned.

While I have described my process with reference to the removal of theskins of filberts, my invention is not to be limited to these, butcovers any kind of nuts, the skins of which may be re moved by myprocess.

I claim:

1. The process of removing the skins of nut meats, which comprisesimmersing the meats with the skins thereon in a'solution ofapproximately 3% of one of the alkalis of the group consisting of sodiumhydroxide, sodium carbonate, sodium bicarbonate and borax for a periodof from one to four minutes, removing the nut meats and rinsing the samein water, immersing the nut meats in a bath of about 2% to 4% solutionof an acid of the group consisting of hydrochloric, acetic and citricacids for a period of from one to four minutes, removing the nut meatsfrom the last mentioned bath, and then subjecting the material to aforcible action of water to remove the skins.

2. The process of removing the skins of nut meats, which comprisesimmersing the nut meats with the skins thereon in a solution ofapproximately 3% of one of the alkalis of the group con- I sisting ofsodium hydroxide, sodium carbonate,

sodium bicarbonate and borax for a period of from one to four minutes,removing the nut meats and immersing the nut meats in a bath of about 2%to 4% solution of an acid of the group consisting of hydrochloric,acetic and citric acids for a period of from one to four minutes,removing the nut meats from the last mentioned bath and then subjectingthe material to a forcible action of water to remove the skins.

3. The process of removing the skin of nut meats which consists inimmersing the nut meats with the skins thereon in a solution ofapproximately 3% of one of the alkalis of the group consisting of sodiumhydroxide, sodium carbonate, sodium bicarbonate and borax, limiting theperiod of such immersion so as to prevent marginal discoloration of thenut meats, removing the nut meats from said solution, then immersing thenut meats in a 2% to 4% solution of an acid-of the group consisting ofhydrochloric, acetic and citric acids, and continuing such 1mmersionuntil looseness of the skins of the nut meats is manifested, and thenefiecting the removing of the skins from the nut meats by water appliedwith a dislodging force.

4. The process of removing the skin of nut meats which consists inimmersing the nut meats with the skins thereon in a solution ofapproximately 3% of one of the alkalis of the group consisting of sodiumhydroxide, sodium carbonate, sodium bicarbonate and borax, limiting theperiod of such immersion so as to prevent marginal discoloration of thenut meats, removing the nut meats from said solution, rinsing the samein water, then immersing the nut meats in a 2% to 4% solution of an acidof the group consisting of hydrochloric, acetic and citric acids, andcontinuing such immersion until looseness of the skins of the nut meatsis manifested, and then effecting the removing of the skins from the nutmeats by water applied with a dislodging force.

EDWARD B. EDES.

